Prior art electronic time-keeping devices, whether wristwatch, wall-mount or table-top clocks, have employed frequency divider methods of time-keeping, wherein the output signal of a stable crystal oscillator is repetitively divided to an appropriate lower frequency and applied to switching, logic and decoding circuits for display to the user as real-time. The calendar date is included in some of these devices such as the one described in U.S. Pat. No. 3,803,834. The same basic circuitry is also used to construct electronic stopwatches.
Frequency divider circuits require as many data lines and decoders as there are dividers to display the data. Thus there is no single data line from which time data can be accessed. Furthermore, for alarm circuits, a plurality of comparators are required. Because of the multiplicity of lines from which the time data must be accessed and the commensurate amount of additional circuitry required use of the data for other purposes such as real-time speed and distance calculations is more difficult.